Carriage control for lathes



E. c. BROOKING 2,368,408

Jan. 30, 1945.

CARRIAGE CONTROL FOR LATHES Filed Nov. 16, 1942 2 Sheets-Sheet 2 N a 4 j r 0 m 4 INVENTOR Li r 3 ECfBrookzb N BY Q i WW1;

irrrs of advancing movement coasts to a stop. 1

in combination in. a lathe, a limit advancing movement Patented Jan. 30, 1945;.

it' -UNITED A maniacs com-nor. roa'na'rmis Edgar O. Brooking; Toccoa, Ga.,

Stockton, CaliL, a, corpora- Tourneau, Inc., a tlon California w N v mber 16, 1942, star-nine ies):

I This invention relates in general to mechanism embodied in 'a machine lathe to automatically ing tool.

One of the objects of the invention-isito prooperativeto positively limit advancing movement of the carriage to" an exact and predetermined point as is necessary where thetool must stopits advance at the same work in the:' lathe; the means toautomatically 'open the circuit of the electric drive motor after the carriage reaches said predetermined point. 3 v

Another object of the invention is to provide point on each' piece of carriage control 'm'echanismas in the preceding paragraph, which includes a compressible carcontrol movement of the carriage whichsup' ports, and advances or-retracts, the work engag vide lathe carriage control mechanism which is I scl imr. (amaz -213' N H I tractlonof the carriage to actuate said assembly to cause the latterto' open said other switch.

of the invention is to Provide A further object a simple and inexpensive device and yet one which will be exceedingly eiiective for the purposefor which it is designed.

"These objects I accomplish by means or such structure and"relative arrangement of. parts as.

mechanism including will fully appear by a specification andclaims.

' e In the drawings similar characters of reference.

indicate corresponding parts in the several views:

Figure '1,is a side elevation 01' a lathe embodying-the carriage control. I

Figure 2 is an enlarged cross section f on Y line 2-2 of.Flgure'1.

riage advancing unit between the lathe feed screw Y 7 An additional object is to provide, in the com bination recited in the preceding paragraph, a switch arranged to be opened to stop the'motor, and a switch control assembly including a movable element disposed to one side of the feed screw clear of the carriage; said carriage advanc .ing means including a not on the feed screw,

compression springs between said nut arid the carriage; there beingan arm projecting from said nut in position to engage and move said element of the switch control assembly.

It is also an object of the invention to provide lathe carriage control mechanism which includes one switch efiective when opened to stop advance of the carriage, another switch effective when opened to stop retraction of the carriage, a switch control assembly operative to open either switch, and means functioning upon predetermined advance of the carriage to actuate said assembly to cause the latter to open said one a certain amount of in said direction after the stop 31s a fragmentary end view illustrating switches as associated with the contact Figure finger of the switch control assembly Figure 4 is a fragmentary'sectional plan taken on line .4-4 of Fig.2.

Referring now more particularly tothe characters of'reference on the drawings, the numeral a indicates the bed of the lathe; the top of said-1 bed being'formed with transversely spaced longitudinally extending ways 2 on which a horizontalcarriage 3 is mounted for longitudinal sliding movement. As here 3 supports a cross slide electric motor l4 connected to said gear box by.

switch, and functioning upon predetermined rewith the work 8 which shown,.the carriage 4 controlled through the medium of a hand wheel 5. The cros slide supports a tool holder 6 and in which holder the tool 1 issecured; the tool rojecting horizontally and longitudinally from the holder for engagement is secured in a driven chuck Son the headstock, of the lathe, indicated generally at vention is here shown embodied, the bed I and the headstock are initially separate, being seinfixed and somewhat spacedrelatio on asuitable base n.

A horizontal 'feed screw I2 is disposed intermediate the ways and extends between the carriage 3- and a gear box I3 mounted in connection with and upstanding from the bed I of the lathe. The feed screw I2 is driven selectivelyv in one direction or the other from the gear box l3, said gearbox being driven by a reversible means of a pulley and belt unit, indicated generally at IS. The motor is actuated by a circuit which includes a switch assembly it ,having switch control buttons l1, l8 and vide a manual control to actuate stop the motor, selectively.

perusal of the following I 0. In the lathe on which the inl9 which pro the motor to advance the carriage, or retract the carriage, or

project through the flange 22 in relative sliding relation thereto and are threaded into the rear end of the carriage:' the shank of bolts 23 be-- ing of such length that when the flange 22 is in engagement with the head of said bolts there is a substantial space between the other face of said flange and the adjacent end of the carriage.

A plurality of heavy duty compression springs 24 are disposed in spaced relation and normally under some compression between the flange 22 and the adjacent end of the carriage. Some of the springs are on the bolts, and escape of the remainder of said compression springs is prevented by relatively short guide studs 25 which 4 project horizontally from flange 22 into'the adjacent end of said springs. The springs 24 normally maintain the flange 22 in engagement with the heads of bolts 23. r

A horizontal shaft 26 is journaled on one side of the bed i in a plane below the ways 2; the journals for said shaft being indicated enerally at 21. The shafts extend from a point below the gear box l3 to a point beyond the point of the carriage. An arm 28 is rigidly secured on the flange 22 of the feed screw nut 20 and extends therefrom laterally and thence downwardly to a termination at its lower end adjacent and laterally out from the shaft 26. The lower end portion of arm 28 is formed as a cam 29 and is adapted to engage and depress a head 30. carried on a stem 3| projecting laterally out from a split block 32 clamped at a selected position on shaft 26. The carriage at its rear end is likewise fitted with a member 33 which includes a cam portion 34 disposed laterally in from shaft 28 and adapted to engage and depress a similarly mounted head 35 projecting laterally -in from another split block 36 secured on shaft 26 rearwardly of split block 32 a distance substantially equal to the travel of the carriage for any given work.

Operation In operation, the stop screw 44 is set to en e the forward end of the carriage when the tool 1 has engaged with the work the desired distance, so that on subsequent work of lik kind the advance of the tool will always be positively limited toapredetermined point.

To advance the carriage from retracted position,-the operator presses button I1 which causes the motor l4. to drive the feed screw in the proper direction. When the carriage has advanced to the limit of its travel, as determined by the position of stop screw 44, the feed screw I2 nevertheless continues to rotate, and the feed screw nut to advance. This latter advance, however, is relatively short and is possible by reason of the fact that springs 24 compress and permit such movement.

After the carriage has engaged the stop screw and the feed screw nut has continued with such relatively short advance, the arm-28 engages and depresses the head 30, rotating the shaft 26 in a direction to swing finger 31 into engagement with and to depress push button 42 on switch box 39. With depression -01 push button 42 the motor is stopped.

To retract the carriage, the operator pushes button l8, which causes the motor H to drive the feed screw 12 in a carriage retracting position. As bolts 23 limit separation of the feed screw nut 29 from the carriage, the carriage is refurthermost forward travel of the rear end of At the end adjacent the gear box l3 the shaft 26 is fitted with an upstanding radial finger 31 which projects between a pair of standard microswitch boxes 38 and 33. respectively, mounted in spaced relation laterally of the lathe on a backboard 40 which is secured to and projects later-' ally from said gear box. The switch boxes 38 and 39 include push buttons 4| and 42 which the upper end of. the finger 31 is adapted to selectively engage and depress with rotation of shaft 26 in one direction or the other. The switch boxes 38 and 39 are wired into the motor control circuit so that depression of the push button 42 opens the circuit of the motor when the motor is running in a direction to advance the carriage, while depression of push button 41 opens the circuit of the motor when the motor is running in a direction to retract the carriage.

The forward end of the bed is provided with a fixed bracket. 43 which projects vertically upward between the longitudinal planes of the'ways to a point above the bottom of the carriage; a horizontallongitudinally extending stop screw 44 being threaded through said bracket and secured in place by a lock nut 45.

tracted with said nut. After the carriage has been retracted the desired distance and suflicient to withdraw the tool 1 from the'work, the cam portion 34 of member 33 engages and depresses head 35. This rocks the shaft 26 in a direction to swing finger 31 into depressingengagement with push button 4| of switch box ,38. When push button 4| is depressed the motor is stopped and the lathe is then ready for the above described cycle to be repeated.

The clamping blocks 32 and 36 are of course adjustable lengthwise of shaft 26 in order to position heads 30 and at the proper point length- 4 wise of the lathe.

By employing compressible means between the feed screw nut and the carriage, it is possible to mechanically and positively stop advance of the carriage at an exact predetermined point, and yet use switch control mechanism which does not require any great exactness or nicety of adjustment. Furthermore, in many gear box and feed screw mechanisms there is a tendency for the feed screw to' coast somewhat 'after the motor is off, and the compressible means between the feed screw nut and carriage permits this coasting without damage to the machine, and which would otherwise occur when the carriage engaged the stop screw 44.

From the foregoing description it will be readily seen that l have produced such a device as subpresent and preferred construction of the device,

still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

l. Carriage control mechanism for a lathe which includes a bed, a carriage mounted for movement along the bed, a driven feed screw, and

after predetermined the feed screw in said 7. Carriage control mechanism -.for a lathe conneCtingthe feed screw with the aaeacoc means connecting the feed screw with the carriage to advance or retract said carriage with rotation of said feed screw in one direction or the other,. respectively; said carriage control mechanism comprising a stop element mounted in connection with the bed of the lathe, the carriage being adapted toengage said stop element advancing movement; said naled along one side connecting means between the feed screw and the carriage including a feed screw nut threaded on the feed screw, and a compression spring engaged between said feed sc'rew nut and the carriage. q v

,-2. A device as in claim 1 including means to nut and the carriage. v

3. A device as in claim 1 including means to limit axial separating movement ofthe feed screw limit axial separating movement of the feed screw.

nut and the carriage, said limiting means comprisinga headed bolt extending parallel'to the feed screw and threaded intothe' adiacentend of the carriage, the feed screw having a portion thereof slid'ably surrounding the shank oi" said headed bolt. v y v 4. Carriage control mechanism for a lathe which includes a bed, a carriage mounted for movement alongthe bed, a driven feed screw, and means connecting the feed screw with the carriage 'to advance or retract rotation of said feed screw in one direction or the other, respectively; said carriage control mech-' anism comprising a stop' element mounted in connectionwith the bed of the lathe, the carriage being adapted to engage said stop element after predete'rminedadvancing movement; said connecting means between the feed screw and the carriage comprising a feed screw nut, a radial flange on thefeed screw nut clear of the adjacent end of the carriage, a plurality ofcompression springs engaged between said flange and said end of the carriage, and means to limit relative separating movement of the feed screw nut and the carriage.

, driven feed screw for necting the feed-screw with the carriage to persaid carriage with .said motor stoppin functioning when element positioned to engage the carriage and limit advancing movement thereof, a motor the carriage, means conmit of a certain, amount of rotation of said feed screwin a carriage advancing direction after engagement of the carriage with saidstop ,element, and feed screw actuated means to stop the motor after the carriage engages said element.

9. A device as in claim 8 in which 'said connecting means includes a feed screw nut; and

means includes an arm projec'ting laterally of the lathe from said'nut, a horizontal shaft journaled on the lathe adjacent v the outer end'of said arm, means on said shaft 25 positioned for engagement by said arm, and

shaft in one direction, a radial finger fixed on said shaft, and a motor shut-off'switch mounted in position to be actuated by saidfinger upon rotation of the shaft in said direction.

10. In a lathe having a bed, and a carriage slidable thereon, a .feed screw, a feed, screw nut,

- a compression spring mounted'between the feed 5,. A device as in claim 4 including locating guide pins projecting from the feed screw nut flange into the compression springs.

6. Carriage control mechanism for a lathe of a certain amount one'direction.

which includes a bed, a carriage slidably mounted on the bed, a motor driven feed screw, and means carriage to advance or retract the carriage with the feed screw in one direction or the other, respectively;' said carriage control mechanism comprising a stop element fixedin position to positively limit advancing movement of the carriage to an exact predetermined point, a switch carriage with rotation ofsaid carriage control mechanism com-- means between the feed; screw and the carriage being arranged topermit Y of continued rotation of.

rotation of which includes a bed, a carriage slidably mounted naled on the bed clear of the cams, a pair of cam engaging screw nut and the carriage, means to limit relatively separating movement of the feed screw nut and said carriage, a reversible electric mo.-

tor connected in driving relation with said feed screw, a pair of motor shut-off switches, one switch being arranged to shut off the motor when advancing the carriage and the other switch being arranged to shut off the motor when retracting ,thecarriage, a stop mounted to limit advancing movement of the carriage, and means operative to actuate said. one switch after i'or-v ward movement of the carriage is so limited, and to actuate said other switch 'after the carriage retracts a predetermined distance.

11-. A device as in claim 10 in which said last namedmeans comprises a horizontal shaft jour-'- carriage and feed screw, an arm secured on the feed nut and projecting to a point adjacent said shaft, a member fixed on thecarriageand extending to -adjacent the shaft, the ends of said army and said "being formed as elements fixed on the-shaft, the arm cam being adapted to engage oneof said elements and rotate the .shaft in one direction after the advancing movement of the'carriage is so limited and the member cam being adapted to engage the other of said ele ments and rotate the shaft i'n'the other direction upon retractionof the carriage said predetermined distance, and a radial finger mounted on said shaft; said finger projectingbetween said switches actuating said one switch when the shaft is. rotated by thearm cam and actuating member adjacent the shaft said other switch when the shaft is actuated by mounted on the lathe and arranged, when actuthe member cam.

' 12. In a lathe having a bed and a carriage slidable thereon, a feed screw, a feedscrew nut, compressible means mounted between the feed screw nut and the carriage, means to limit relative separating movement of the feed screw nut and said carriage, a reversible electric motor so engaged, to rotate said connected in driving relation with said teed screw, apair of motor shut-off switches arranged to shutoflthe motor when the latter is advancinglthe carriage or when retracting the carriage, selectively, a stop element mounted to.

positively limit advancing movement of the carriagegand means to actuate said one switch after forward movement of the carriage is so limited,

positively stop the carriage at a predetermined point in its advance, means to permit the screw ,to continue to rotate after the carriage has stopped, a movable control element operative to stop the motor, and feed screw advancedmeans separate from the carriage and operative to engage and move said element after the carriage has engaged the stop. a

14. Carriage control mechanism for a lathe which includes a slidably mounted carriage, reversible drive means, a feed screw driven by the drive means and connected with the carriage to advance the latter with the forward turning movement of the screw and to retract the carriage with the backward turning movement of such screw, means to positively stop the carriage at a predetermined point in its advance, means to permit the screw to continue its forward turning movement after the carriage has stopped, means including separate movable control ele- ,ments adapted to stop said drive means when the screw has been rotated a certain predetermined amount in either direction respectively, screw advanced means separate from the carriage and operative, with the forward turning movement of the screw, to engage one of said elements after the carriage has been stopped, and means on the carriage to engage and move the other element when the screw is turned in the other direction and has retracted the carriage a predetermined distance.

15. Carriage control mechanism for a lathe which includes a slidably mounted carriage, a feed screw connected with the carriage to advance or retract the same upon rotation of said screw in one direction or the other, reversible drive means for said feed screw, means including separate movable control elements adapted to stop said drive means upon predetermined advance and retraction respectively of the carriage, teed screw advanced means separate from the carriage operative to engage and move the corresponding one of said elements upon said predetermined advance of the carriage, and means on the carriage to engage and move the other of said elements upon said predetermined retraction of the carriage; there being a fixed stop positioned to engage and positively stop the carriage upon said predetermined advance thereof, and means between the feed screw and carriage operative to permit of limited continued rotation of the feed screw after the carriage engages said stop.

EDGAR C. BROOKING. 

